On Jul 1, 2:43 pm, Kurda Yon <[EMAIL PROTECTED]> wrote: > Hi, > > I have a class called "vector". And I would like to define a function > "dot" which would return a dot product of any two "vectors". I want > to call this function as follow: dot(x,y). > > Well, I can define a functions "dot" outside the class and it works > exactly as I want. However, the problem is that this function is not > associated with the class (like methods a method of the class). > > For example, if I call "x.calc()" or "y.calc()", python will execute > different methods if "x" and "y" belongs to different classes. I want > to have the same with my "dot" function. I.e. I want it calculates the > dot product ONLY IF the both arguments of that function belong to the > "vector" class. > > Is it possible? > > Thank you in advance.
If I understand what you want, you could do it the same way most of the other functions are implemented. There's a function, and then each class which has the behavior has a private (actually a system) method that implements it. The general pattern is to get the class for the first operand, check to see if it has the implementation method, and call it if present. If it doesn't, get the class for the other operand, check and if it has the method call it with the operands reversed. Then if it isn't in either, you can look the actual implementation method up in a table. When all else fails, raise a type error. HTH John Roth -- http://mail.python.org/mailman/listinfo/python-list
